This invention relates to the chemical modification of textiles and fibers and more particularly, the chemical modification of proteinaceous textiles of fibers by contact with an aqueous solution of a sulfite to impart wash and wear characteristics.
Much of the material in this application was also presented in U.S. Application Ser. No. 61,183, filed Aug. 5, 1970, now abandoned, and in Application Ser. No. 481,105, filed June 20, 1974, now abandoned.
Fabrics consisting wholly or in part of wool have long been known to undergo undesirable changes in physical characteristics during washing, including excessive wrinkling and a pronounced tendency to felt or shrink. Therefore, a method has long been sought to provide an effective process for preventing or minimizing this wrinkling and shrinking of wool. Numerous solutions to this problem have been advanced largely in the nature of chemical treatment which may be classified as halogenation, oxidation, reduction, alkaline, enzyme, or resin treatments. However, with a treatment of wool or other keratinous fibers or cotton to reduce wrinkling and shrinking, it is also necessary that other changes do not occur in the fibers so as to result in a diminution of the hand, appearance, color, strength, and other desirable properties of the original wool or wool containing material.
In connection with the above processes, it is common practice to treat a woolen fabric, first with a solution of an oxidizing agent and then with a solution of a reducing agent. Typical reducing agents include aqueous solutions of various sulfites and consequently, sulfites are in common usage in procedures for imparting wash and wear characteristics to woolen fabrics. For example, in U.S. Pat. No. 3,097,913, a process is disclosed comprising treating a woolen fabric with an oxidizing solution maintained at about 50.degree. F. to 100.degree. F. containing from about 0.1 to 0.4 percent by weight of oxidizers selected from peracetic acid and mixtures of peracetic and potassium permanganate at a pH less than 7 and thereafter treating such fabric with a reducing solution maintained at about 65.degree. F. to 140.degree. F. having a concentration of from about 0.5 to 5.0% by weight of an alkaline metal or alkaline earth metal salt of a sulfite or bisulfite. The period of contact with the oxidizing solution typically ranges from about 10 to 30 seconds and the contact with the reducing solution typically ranges from about 10 seconds to 45 minutes.
In U.S. Pat. No. 2,739,034, a process for treating wool fabrics to prevent shrinkage is disclosed comprising treatment of the wool fabric with an oxidizing solution of permonosulfuric acid at a pH less than 8 followed by contact with a reducing solution consisting of normal, acidic or basic salts of sulphurous acid which salts would include sulfites. The teaching in said patent is that if concentrated sulfite solutions are used, contact time and solution temperature are low. If dilute sulfite solutions are used, contact time and temperature may be increased.
As incidental disclosure in the aforesaid U.S. Pat. No. 2,739,034, there is disclosed the use of zinc sulfite alone as a treatment for wool. In this respect, a wool fabric was rinsed with water and treated at 25.degree. C. for 30 minutes in a bath containing 0.5% zinc sulfite. It is reported that this treatment is ineffective inasmuch as the area shrinkage is 22%.